Illuminating fixture



Nov. 9, 1943.

J. A. HOEVELER 2,334,005

LLUMINATING FIXTURE Filed Aug. 5, 1941 Q Nl vmaterial most commonly used being glass.

4characterized by numerous objections.

UNITED STATES PATENT OFFICE ILLUll/INATING FlDi'IURE` John A. Hoeveler, Mount Lebanon, Pa., assignor to Pittsburgh Reflector Company, Pittsburgh, Pa., a corporation of New Jersey Application August 5, 1941, Serial No. 405,511

(Cl. Mil-JIS) 2 Claims.

This invention relates to illuminating fixtures and, in particular, to a fixture specially adapted :to accommodate a tubular light source, such as `a fluorescent tube.

Fluorescent-tube fixtures have been brought on'the market recently in a wide variety of types and designs. It has been found that better illumination is provided, from the standpoint of uniformity and absence of glare, when these xtures incorporate a diffusing screen or an enclosure for the tubes themselves. Various types of screens or enclosures have been proposed, the Glass screens or enclosures for fiuorescent tubes are In the first place, they are quite heavy. A definite `hazard to those working or passing below the fixture is present, therefore, in case of failure of the support for the enclosure. This hazard is also present when, as is periodically necessary, the

screens are removed for cleaning. The danger of breakage inthe handling incident to installation or removal for cleaning is also a disadvantage.

I have invented a novel illuminating fixture.

including a diffusing screen or enclosure which fully overcomes the aforementioned disadvantages of the customary glass enclosure. I provide a diffusing screen composed of a lighttransmitting sheet of organic resin, preferably having a novel form of surface treatment, which is specially adapted for use with elongated or tubular light fixtures such as the standard fiuorescent tubes. The sheet is preferably very thin so that it has a good light transmission factor and is preferably provided with longitudinal corrugations to lend rigidity thereto. The surface of the sheet, furthermore, may have longitudinal ribs arranged in spaced groups, the area of the sheet between groups of ribs having a surface condition similar to nurling. The sheet is bent in the form of a portion of a cylinder and is provided with detachable mounting means whereby it may be readily removed for inspection or cleaning.

Further details of the invention will become apparent during the following description and explanation which refers to the accompanying drawing illustrating a preferred embodiment. In the drawing,

Figure l is a side elevation with a portion broken away;

Figure 2 is a transverse sectional view taken on the plane of line II-II of Figure 1; and

Figure 3 is a partial plan view of the sheet forming the diffusing screen for the tubular' light source.

Referring now in detail to the drawing, the fixture of my invention includes a shallow channel or flanged plate II) serving as a base or principal support for the remaining elements of the fixture. The plate I0 may be supported byhangers i I suspending fro-m the ceiling or, in the case of a ceiling-type fixture, may be secured directly to the ceiling by suitable means.

Elongated trough-like reectors I2 are disposed side by side, with their edges lying in an arcuate surface. The edges of adjacent reflectors are secured together by channel strips I3 and the edges of theV outermost reflectors are secured to inturned flanges I4 on the plate IU bybolts I5. While the reflectors I2 are illustrated as polygonal in section, they may be arcuate as well.

A trough-like member or channel I6 yextends longitudinally of the fixture behind and in contact with the reflectors I2. The member I6 provides a support for auxiliary devices such as ballast reactors I'I. Lamp holders I8 are positioned adjacent the ends of the reflectors I2,

the bottoms of the latter and the bottom and sides of the channel I6 being suitably cut out to receive them. Fluorescent tubes I9 are inserted in each pair of holders, the latter being so placed that the tubes are appropriately positioned relatively to the refiectors I2.

The ends of the fixture are closed by end caps or covers 20. Each cover includes a plate 20a and a ring 2Gb secured thereto by thumb screws 2te. The plates 2Ga are secured to brackets 2| welded to the plate I0, by thumb screws 2Ia.

A diffusing screen or enclosure 22 extends around the group of reflectors I2 and from one end cap 2U to the other. This screen is composed of a relatively thin sheet 23 (i. e., about .04" thick) of light-transmitting material, preferably an organic resin such as cellulose acetate, and may be either clear or translucent. The sheet 23 is bent to a generally cylindrical curvature as shown in Figure 2 and has corrugations 24 longitudinally thereof. The edges of the sheet have sheet-metal binding strips 25 secured thereto in any suitable manner. These binding strips are detachably secured to flanges Illa of the plate I0 by thumb screws 2S, the strips being slotted so they can be removed by simply loosening the screws 26.

If the material of which the sheet 23 is composed is translucent, it is a natural light diffuser.

The corrugations 24 increase the diffusing effect of the sheet 23. If the material is clear, the diffusing eifect is provided by a surface treatment applied to the exterior of the sheet. 'I'his surface treatment comprises the formation of raised ribs 21 arranged in spaced groups, as shown in Figure 3. These ribs are formed by dies under pressure, one of the dies having fine lines or grooves cut in its surface whereby to form ribs on the application of pressure. Thesheet 23 is preferably subjected to the action of the dies while in the flat.

Between the spaced groups of ribs 21 the surface of the sheet 23 has imparted to it a condition similar to nurling as indicated at 28. nurled surfaces 28 are preferably at the troughs and crests of the corrugations 24. Both the nurled areas and spaced groups of ribs serve in cleaning. The screen may be easily removed by merely taking out the screws 26, after removing one of the rings h. The screen also improves the appearance of the fixtureas a whole. It also prevents fragments of the fluorescent tubes from falling in case of breakage thereof.

Although I have illustrated and described but a preferred embodiment of the invention, it will be recognized that changes in the design and arrangement of the various parts may be made without departing from the spirit of the invention as defined in the appended clahns.

The.

an obvious manner to give the screen 22 a difi fusing eiect on the light from the tubes I9 and reectors I2, passing therethrough. The nurled surfacesA are formed in the same manner as the ribs 21 and preferably at the same time.

'It will be apparent from the foregoing description and explanation that the invention is characterized -by numerous advantages over diffusing screens as proposed heretofore for fluorescent tube fixtures. In the rst place, the screen of my invention is extremely light in weight but at the same time is quite strong. Since it is quite flexible, it is not subject to much danger of breakage in the handling, Whether during installation or in removal for cleaning or inspection. The longitudinal rigidity imparted by the corrugations, as well as the generally cylindrical shape of the sheet, is such that a relativelythin sheet may be i employed. The light transmitted through the sheet is greater, of course, the smaller the thickness of thesheet. As previously mentioned, furthermore, the corrugations as Well as the surface treatment of the sheet provide a diffusing effect much greater than that characterizing other types of screens, i. e., translucent glass screens. Because of the light weight of the screen of my invention, there is little or no hazard to those working or walking beneath the fixtures by reason of the danger of a screen falling as when, for example, being removed for I claim:

1. An illuminating fixture comprising an elongated supporting member, having spaced end caps secured thereto, means mounting aplurality of tubular lamps on said member, and a diffusing screen bent around sald lamps and defining with said member and end caps an enclosure therefor, said screen being composed of a sheet of flexible light-transmitting material, said sheet being corrugated `longitudinally by displacement of the material thereof in opposite directions from its original plane, and thereby given sufficient rigidity to make it self-sustaining in shape between said end caps, the exterior surface of said sheet having ribs formed thereon parallel Vto the corrugations, there being a multiplicity of ribs in each corrugation.

2. An illuminating fixture comprising an elongated supporting member, having spaced end caps secured thereto, means mounting a plurality of tubular lamps on said member, and a dif.- fusing screen lbent around said lamps and defining with said member and end caps an enclosure therefor, said screen being composed of a sheet of flexible light-transmitting material, said sheet being corrugated longitudinally by displacement of the material thereof in opposltefdirections from` its original plane, and thereby giv.- en sufficient rigidity to make it .self-sustaining in shapebetween said end caps, the troughs and crests only of the corrugations` being roughened, thereby providing alternating stripes of contrasting appearance.

JOHN A.HOEVELER. 

